Document Type

Article

Publication Date

3-1-2021

Abstract

Significant interest in two-dimensional transition metal dichalcogenides has led to numerous experimental studies of their synthesis using scalable vapor phase methods, such as chemical vapor deposition (CVD) and atomic layer deposition (ALD). ALD typically allows lower deposition temperatures, and nucleation of chemical precursors requires reactions with surface functional groups. A common first-principles method used to study ALD modeling is the calculation of activation energy for a proposed reaction pathway. In this work we calculated the partial charge densities, local density of states (LDoS), Bader charge analysis, adsorption energies, and charge density difference using density functional theory (DFT) to investigate the nucleation of MoF6 on three oxide surfaces, including Al2O3, HfO2, and MgO. Our findings indicate that hydroxyl groups (OH) help lower the reaction barrier during the first half-cycle of MoF6 and promote the chemisorption of a precursor on the oxide substrates. This discovery is supported by the formation of highly ionic MFx (M = metal, x = 1, 2, 3) bonds at the oxide surfaces. By comparing surfaces with and without hydroxyl groups, we highlight the importance of surface chemistry.

Copyright Statement

This is an author-produced, peer-reviewed version of this article. © 2021, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International license. The final, definitive version of this document can be found online at Applied Surface Science, https://doi.org/10.1016/j.apsusc.2020.148461.

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